Fountain integration

You know what would be nice? A function (inside the package) that transforms Fountain markup language to your Typst screenplay language. See [Better Fountain](https://github.com/piersdeseilligny/betterfountain) or [AfterWrite](https://github.com/ifrost/afterwriting-labs) for inspiration.

In a sense a fountain renderer using typst would be really nice.